The Medieval Church · c. 885
The Mystagogy of the Holy Spirit
Photius of Constantinople · c. 815–c. 893
What it is
A sustained argument that the Spirit proceeds from the Father alone, and that the Latin addition to the creed is both unauthorised and incoherent.
Why it lasted
The definitive Eastern case against the filioque, and a permanent fixture of every subsequent East–West negotiation.
Scripture it works from
Where to read it
This work is in the public domain and can be read in full, free, at the archives below. The Library catalogues it; it does not host the text.
These open a search on each archive rather than a direct link, which is the honest way to point at an edition nobody here has checked line by line.
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